"""
Overview:
    Import functions, may be useful when support some dynamic features (such as imports in cli development).

    This module provides utilities for dynamically importing Python objects, modules, and attributes.
    It supports pattern matching and flexible import strategies for runtime object resolution.
"""
import builtins
import fnmatch
import importlib
from itertools import islice
from queue import Queue
from typing import Optional, Callable, Any, Tuple, Iterator

from .func import dynamic_call

__all__ = [
    'import_object',
    'quick_import_object',
    'iter_import_objects',
]


def _import_module(module_name: Optional[str] = None):
    """
    Import a module by name or return the builtins module.

    :param module_name: Name of the module to import. If None, returns builtins module.
    :type module_name: Optional[str]
    :return: The imported module or builtins.
    :rtype: module

    Example::
        >>> _import_module('os')  # Returns os module
        >>> _import_module(None)  # Returns builtins module
    """
    if module_name:
        return importlib.import_module(module_name)
    else:
        return builtins


def import_object(obj_name: str, module_name: Optional[str] = None):
    """
    Dynamically import an object from a module.

    This function imports a specific object (class, function, variable, etc.) from a given module.
    If no module name is provided, it searches in the builtins module.

    :param obj_name: Name of the object to import.
    :type obj_name: str
    :param module_name: Name of the module containing the object. 
        Defaults to None, which means the builtins module.
    :type module_name: Optional[str]
    :return: The imported object.
    :rtype: Any
    :raises AttributeError: If the object does not exist in the module.
    :raises ModuleNotFoundError: If the module cannot be found.

    Example::
        >>> import_object('zip')               # <class 'zip'>
        >>> import_object('ndarray', 'numpy')  # <class 'numpy.ndarray'>
    """
    return getattr(_import_module(module_name), obj_name)


def quick_import_object(full_name: str, predicate: Optional[Callable] = None) -> Tuple[Any, str, str]:
    """
    Quickly dynamically import an object with a single name.

    This function attempts to import an object using its full dotted name, supporting
    nested attributes. It returns the first matching object along with its module and name.

    :param full_name: Full dotted name of the object, attribute access is supported.
    :type full_name: str
    :param predicate: Optional predicate function to filter results. 
        Should accept (obj, module_name, obj_name) and return bool.
        Defaults to None, which means no filtering.
    :type predicate: Optional[Callable]
    :return: A tuple containing (imported_object, module_name, object_name).
    :rtype: Tuple[Any, str, str]
    :raises ImportError: If the object cannot be imported.

    Example::
        >>> quick_import_object('zip')                     # (<class 'zip'>, '', 'zip')
        >>> quick_import_object('numpy.ndarray')           # (<class 'numpy.ndarray'>, 'numpy', 'ndarray')
        >>> quick_import_object('numpy.ndarray.__name__')  # ('ndarray', 'numpy', 'ndarray.__name__')
    """
    _iter = islice(iter_import_objects(full_name, predicate), 1)

    try:
        # noinspection PyTupleAssignmentBalance
        _obj, _module, _name = next(_iter)
        return _obj, _module, _name
    except (StopIteration, StopAsyncIteration):
        raise ImportError(f'Cannot import object {repr(full_name)}.')


def iter_import_objects(full_pattern: str, predicate: Optional[Callable] = None) \
        -> Iterator[Tuple[Any, str, str]]:
    """
    Quickly dynamically import all objects matching a full name pattern.

    This function yields all objects that match the given pattern, supporting wildcards
    in attribute names. It performs a breadth-first search through module attributes
    to find all matching objects.

    :param full_pattern: Full pattern of the object with wildcard support. 
        Supports fnmatch-style patterns (e.g., 'numpy.array*').
    :type full_pattern: str
    :param predicate: Optional predicate function to filter results.
        Should accept (obj, module_name, obj_name) and return bool.
        Defaults to None, which means no filtering.
    :type predicate: Optional[Callable]
    :return: Iterator yielding tuples of (imported_object, module_name, object_name).
    :rtype: Iterator[Tuple[Any, str, str]]
    :raises ModuleNotFoundError: If no valid module can be found in the pattern.

    Example::
        >>> list(iter_import_objects('os.path'))  # Yields all matching objects
        >>> list(iter_import_objects('numpy.array*'))  # Yields all numpy objects starting with 'array'
    """
    predicate = dynamic_call(predicate or (lambda: True))

    segments = full_pattern.split('.')
    length = len(segments)
    _errs = []
    for i in reversed(range(length + 1)):
        module_name = '.'.join(segments[:i])
        attrs = tuple(segments[i:])
        attrs_count = len(attrs)

        try:
            module = importlib.import_module(module_name or 'builtins')
        except (ModuleNotFoundError, ImportError):
            continue

        queue = Queue()
        queue.put((module, 0, ()))
        exist = False

        while not queue.empty():
            root, pos, ats = queue.get()

            if pos >= attrs_count:
                obj_name = '.'.join(ats)
                if predicate(root, module_name, obj_name):
                    yield root, module_name, obj_name
            elif hasattr(root, attrs[pos]):
                queue.put((getattr(root, attrs[pos]), pos + 1, ats + (attrs[pos],)))
                exist = True
            elif hasattr(root, '__dict__'):
                for key, value in sorted(root.__dict__.items()):
                    if fnmatch.fnmatch(key, attrs[pos]):
                        queue.put((value, pos + 1, ats + (key,)))
                        exist = True

        if exist:
            break
